Copper Pipes and Tubes in Straight Lengths and Coils

DHP copper carries 0.015–0.040 % phosphorus, which removes the oxygen during casting. With no copper oxide inside, there is nothing for hydrogen to react with when a brazing flame heats the joint, so the tube cannot suffer the steam cracking that affects ETP copper. The cost is conductivity, around 85 % IACS instead of 100 %, which does not matter for a tube carrying refrigerant or water. Our E.C. grade copper page explains the hydrogen problem in more detail.

DHP also flares, swages and expands well, and its slightly higher recrystallisation temperature helps tube keep its drawn temper during handling.

Straight lengths are supplied drawn (hard). They stay straight on the rack and in exposed runs, take less support, and suit plumbing risers, medical gas manifolds and visible pipework. Joints are made with fittings and brazing.

Coils are annealed (soft). An installer can bend them by hand or with a lever bender, flare the ends and run long lengths with very few joints. Split AC line sets and refrigeration connections are almost always run from soft coils. Coil tube is also the usual choice where a single length has to snake through walls and false ceilings.

Medical gas lines are a special case. Hospitals generally ask for hard tube that has been degreased and capped for oxygen service, made to EN 13348 or an equivalent specification, and joined by brazing under a nitrogen purge. If your job is a hospital pipeline, say so at enquiry, because ordinary plumbing tube is not cleaned to that level.

ACR stands for air conditioning and refrigeration. ACR tube to ASTM B280 is sized by actual outside diameter in inches (1/4", 3/8", 1/2", 5/8", 3/4" and so on, matching flare nuts and fittings), cleaned inside to a low residue limit, and capped at the ends so moisture and dirt stay out until installation. Dirt and moisture are the enemies of a refrigeration circuit, so keep the caps on until the moment of brazing. In Europe the equivalent is EN 12735-1.

Wall thickness matters more now than it used to. Newer refrigerants such as R-410A and R-32 run at higher pressures than R-22, so check the wall your AC manufacturer specifies rather than buying the thinnest tube on offer.

These are wall-thickness classes in ASTM B88, the American standard for water tube. All three share the same outside diameter for a given nominal size, so they take the same fittings; only the wall changes. Type K is thickest and is used underground and for higher pressures; Type L is the general-purpose wall for interior plumbing, heating and many medical and gas installations; Type M is thinnest and used for low-pressure domestic lines where codes allow. Tubes are marked along the length with a colour code: green for K, blue for L, red for M. European plumbing tube follows EN 1057 instead.

Indian-made tube is commonly supplied to IS 2501 for general engineering or to customer drawings, and imported tube usually to ASTM or EN standards. Both are DHP copper. What matters is that the standard on the certificate matches the standard on your drawing, particularly for wall thickness and temper. If a project specification names a standard, quote it in the enquiry and we will offer tube that matches.

Coil tube is normally sold by coil, with a nominal length such as 15 m or by coil weight, and straight tube by length or kilogram. Ask for both figures on the quotation so offers can be compared fairly.

For a quick quote on copper pipe in Bangalore, send outside diameter (inch or mm), wall thickness or type, straight or coil, length or coil weight, quantity, and the standard. We confirm what is available in your size when we quote. For larger heat exchanger work, see also our brass pipes and tubes, and for HVAC projects, our refrigeration and HVAC page.